ON Semiconductor NCV7748 User Manual
NCV7748GEVB
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NCV7748 Evaluation Board
User's Manual
Eight Channel Low-Side Relay Drivers
with LIN Communication
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Description
The NCV7748 is an octal low-side relay driver for automotive
applications targeted for use in a Power Distribution Box (PDB).
Communication to the device is through a LIN bus compliant to SAE
J2602 and LIN 2.x. All drivers have passive output clamps for limiting
output voltage spikes during flyback events during inductive relay
turn-off events.
This evaluation board is intended for evaluation of the output
drivers, and highlights many of the features of the device.
The NCV7748 has two types of low-side drivers. One is intended to
run outside of the module and the other is targeted for use inside the
module. All outputs have Overcurrent Detection, but the output
drivers intended for use external to the module (OUT4, OUT8) have
added Open Load detection and individual Overtemperature (Thermal
Shutdown) detection. The evaluation board includes NEC EX2
automotive relay loads, with the option to disconnect these loads and
use customer defined external loads.
Output control is interfaced with the use of dip switches and
a push-button. Output Control Commands as well as Output errors can
be read from the LCD display. Truth tables are included in silk screen
on the PCB for ease of use for both command control and error
deciphering.
Features
• Individual Output Drive Control
• On-board Relay Demonstration with Option for Off-board
Connections
• Get Status Request for Error Reporting from ERR and APPINFO
Registers
Application
The NCV7748 device includes 8 low-side drivers. Each includes an
output clamp for inductive loads. A 41 V (typ) clamp from the drain to
gate of the output driver helps protect the output driver from seeing
excessive voltage during a flyback event from an inductive load. The
minimum specification for the clamp voltage is 38 V. It is important to
limit external DC supply voltages to less than 38 V to avoid a high
power situation.
Primary target loads are coils of relays for a power distribution box
(PDB). These can include, but not limited to loads for Engine Control
Unit (ECU), Windshield Wipers, Sunroof, Cruise Control, Rear
Window Defroster, Fog Lights, Cooling Fans, Ignition, Headlights,
Tail Lights, Hazard Lights, Horn, Cooling Fan, Cluster, Heated
Mirror, External Accessory Voltage, Instrument Cluster, Keyless
Entry, Fuel Pump, etc.
EVAL BOARD USER’S MANUAL
Figure 1. NCV7748 Evaluation Board
41 V
(Typ)
1.5 W
(Typ)
Over CurrentFault
Figure 2. 1.5 W Output Drivers
41 V
(Typ)
0.8 W
(Typ)
Thermal Shutdown
Over Current
Fault
Figure 3. 0.8 W Output Drivers
Open Load
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
© Semiconductor Components Industries, LLC, 2016
July, 2016 − Rev. 0
1 Publication Order Number:
EVBUM2484/D
NCV7748GEVB
Communication
The NCV7748 utilizes a LIN protocol for all
communication. LIN is a single wire communication
network which utilizes a master/slave configuration. The
NCV7748 is the slave and receives its commands from an
To
Control
Block
LIN Address
LIN
Protocol
Handler
external master device and also reports on the same pin
(LIN) to the master device after a request is made. Figure 4
shows the basic LIN schematic. The LIN bus is driven high
through a 30 kW resistor in series with a diode and its read
capability is filtered to an internal RxD comparator.
VBB
30 kW
RxD
−
+
TxD
Filter
Slope
Control
LIN
From NAD Register
Figure 4. LIN Controller
A table (Table 1) of supported commands of the
NCV7748 is listed below from the NCP7744/D data sheet.
comprised of 4 outputs instead of the 8 outputs of the
NCV7748.
Note the NCV7744 reference is to a sister part which is
Table 1. SUPPORTED LIN COMMANDS
PID[7:0] Frame Type Description Data Length Spec
Depends on NAD Output Control Sets all outputs in one virtual node. 8 N/A
Depends on NAD Get Node ID Reads identity of prime device in virtual node.
Depends on Rconfig
and NAD
0x3C Targeted Reset
0x7D Targeted Reset
0x3C Read by Identifier
0x7D Read by Identifier
0x3C Broadcast Reset Re-initialization of all nodes. 8 J2602−1
0x3C Goto Sleep All devices enters Sleep Mode. 8 LIN2.2
Get Status Reads diagnostics of one device (LS driver).
Master Request
Slave Response
Master Request
Slave Response
(In frame slave Response)
(In frame slave Response)
Re-initialization of one virtual node.
This includes all devices on the virtual node.
Positive response by prime device. 8
Reads identity of device supplier. 8
Successfully processed request. 8
Slave could not process the request. 8
8 N/A
8 N/A
8
J2602−1
LIN2.2
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NCV7748GEVB
The NCV7748GEVB is capable of demonstrating:
• Output Control
A one-way command which sets all outputs in one
virtual node (see NCP7744/D data sheet for virtual
node definition).
• Get Status
A two-way command which requests device
diagnostics and receives a response with an in-frame
response.
• Display of Sleep Mode
After timeout.
Practical setup limitations do not allow the display of Get
Node ID, Targeted Reset, Read by Identifier, Broadcast
Reset, and Goto Sleep on this board. A further enhanced
setup using enriched software is needed to display all device
features.
Table 2. MAXIMUM RATINGS
Rating Value Unit
Supply Voltage to Board (14VDC) (Using On-board NEC Relays) −0.3 to 16 V
Supply Voltage to Board (14 VDC) (Removing LOAD1−8 Jumpers) −0.3 to 40 V
TxD −0.3 to 5.25 V
RxD −0.3 to 5.25 V
LIN −40 to 40 V
Output Pin Voltage (OUT1− OUT8) (Removing LOAD1−8 Jumpers) Using External Loads −0.3 to 38 V
Junction Temperature (NCV7748) −40 to 150 °C
Temperature (Evaluation Board) −40 to 105 °C
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
The operation of the NCV7748 evaluation board works as
a standalone presentation for the customer highlighting LIN
communication for turning on and off low-side drivers (both
1.5 W and 0.8 W). Dip switches provide the user
programmability for the Control Frame. Jumpers provide
convenient access to TxD, RxD, and the LIN pin which are
normally connected to the on-board microprocessor.
Jumpers are also included for use with external loads.
A jumper is included to maintain output control to avoid
going to sleep after the NCV7748 “Time to go to sleep”
electrical parameter. Pushbuttons are included for
implementing the user control of Output Control and Get
Status. Pushbuttons are also included to provide overcurrent
conditions (OCD) of the loads. A demo mode is provided via
a toggle switch.
The user must adhere to the absolute maximum ratings
when using off-board connections.
Table 3. RECOMMENDED BOARD OPERATING CONDITIONS
Rating Min Max Unit
External Supply Voltage (14VDC) − 16 V
Junction Temperature (NCV7748) −40 150 °C
Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond
the Recommended Operating Ranges limits may affect device reliability.
Table 4. PIN FUNCTION DESCRIPTION
Connector Pin Number Terminal Name Description
Power
Test Points
J12, J13 14 VDC Power Supply Input Voltage (14 V)
GND GND Ground
J1 LIN LIN Bus
J2−8, J11 LOAD 1−8 On-board Relay Disconnect
J9 OUTPUT CONTROL LIN Command for Output Control (Pushbutton Shorts to Ground)
J10 HEADER 16 Header for LCD Display
J14−J19 N/A Board Post Mount Holes
J20−J23 N/A LCD Display Post Mount Holes
J24 TxD NCV7321 TxD Input
J25 RxD NCV7321 RxD Output
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User Interface Locations
Figure 5 shows all the user interface locations. This lists
all the user options available on the evaluation board.
NCV7748GEVB
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1. OUT1−8 External Post Connections
2. External Relay Jumpers
3. Overcurrent (OCD) Pushbuttons
4. TxD, RxD Jumpers
5. LIN Test Point
6. Output Control Command Input Data
7. Output Control Pushbutton
8. LOOP Jumper for Continuous Operation
without Four Second Timeout
9. Get Status Pushbutton
10. Demo Mode Toggle Switch
11. 14 VDC Power Supply Inputs
12. LIN Auxiliary Input
Figure 5. User Interface Locations
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